Enjoyed the video very much, thank you

Interesting point about power supply cable being wrong. I now will be checking everything.

Great job! Looks like it regulates very well. RJ

I think that 0.1Ω it's too low for a balance resistor, on most design I always saw something on the 0.22Ω-0.47Ω region, it will matter a lot on the worst case scenario, something like 30V IN, 0.5V at 5A OUT, I think at least an extra tap should be mandatory for linear supplies with this amount of power. Transformers with a center tap, something like 9v-0-9v or 12v-0-12v are very common. Really nice design/project over all👍

Sorry I just grabbed the circuit and had a look :-) It should be a bit better than that. It looks like you are sensing the output voltage before the 0,1 ohm resistors, so that will make the regulation worse, but not too much in a general purpose supply. You should be looking for about 0.15 to 0.2V across the resistors. It's a bit empirical as it does still depend on the transistors being reasonably closely matched and in good thermal contact. Andy

This is really helping me grasp a better understanding, I've been involved with electronics for 45 years, but due to life getting in the way, I never completed any formal training, although not for the lack of trying in the early years, I worked without pay at a TV repair shop when I left school in 84 in hope of getting an apprenticeship, I was doing repairs and antenna installations for 6 months and right in front of me they gave the apprenticeship to someone else, it was really demoralising the 2 other technicians couldn't understand it either. I left and never went back, My primary interest was digital and computers with some programming and self educating as I went along ,the trouble is I tended to skip over essentials not relevant to what I was doing at the time only to have to backtrack later. I'm still backtracking.

Put a small resistance in the power transistor emitters, say 0.1 ohm that will give a little bit of negative feedback and stop one transistor taking all the load. Andy

Epic little project is the current schematic upto date and available please.

Ace!

Clevland?

Split into two categories? LCR meters (AC) and Tweezer DMM's (DC). Some of the DC ones are uniquely good as Zener diode testers. Some things to look out for. (1) You would think the ones that measure battery voltage would be good for coin cells, but the current drawn is way too much for them. Voltage on these can be tested reverses biased, which does not load the cell. (2) The holdpeak leads are truly terrible. Mine came from the factory with black spots in the plug plating and an intermittent connection on the red pen. The holdpeak battery bay is also too small for NiMH cells and Lithium primaries. The springs must be cut down if you want to use them. It does power off by holding one of the two buttons. (3) The Uni-T not only lacks a power off, the quiescent current is much higher than most devices. It will eat batteries, even when off. (4) If the Uni-T case is too hard to remove, you can loosen the screw close to the wide end or put a washer between the two halves near that end. I put a piece of red heat-shrink tube on the + arm.

I'm looking forward to seeing your results on which you think is the best one before I buy one!

The UNI-T is the only one that will light an LED under test. The metal plate on the Fnirsi has adhesive on one side and can be attached to your work station to act as a magnetic base for the tweezers.

I'd guess the metal plate is used for calibration.

Oh one of each! How about an analog one with a mech needle?

Scan the instruction and send it to google translate as a file and get a translated file back.

What is the model of your silver LCR meter? Why did you get the ET4410 if you had the silver meter?

The "leads" of the Uni-T. ODD to say the least.

How do you know before you buy it what is a good SMPS? They all look the same on websites.

Bought it approx. 6 years ago for 35 EUR. Didn't expect that it will handle 20 MHz, but for low frequency it does it's job. Even today for such money you will be able to buy only something similar, not much better, so 6 years ago it was a good buy for it's price. People who buy such tools are not able to buy scope for three or five hundred bucks and, in fact, they don't need it for their tasks.

So you put like: (24 * sqrt(2) - 1.5V - 19.5V) * 5A = 65W into these skinny heatsinks, via paralleled but not verified to share current TO-247 packages. In my tests I find the comfortable operating limit of single TO-264 actively cooled on a 5mm base ("needle" fin) heatsink from Ali (150x130x17mm) to be around 90-100W. That's way more heatsink mass, less thermal resistance on both HS base and BJT package.. TO-247 I tried on it as well, IIRC it did handle around 20-40W realistically, YMMV depending on how good the die connection is. P.S. Lower ESR on a 50/60 Hz FBR is actually counterproductive.

Alot more minis on yhe market not featured here. They are improving slowly

I'm not sure about the following comment. Do you have to match the transistors or drive them separately to prevent one from doing all the work.

Nothing like a challenge. If life was simple, we would all be doing it. Keep warm 🎿

That’s too bad, I was excited to see it finished. I know you will get it resolved and fully functional. Looks really good! RJ

Oh well !! see ya next time.....cheers.

7:02 Famous last words 😮

awesome upgrades

Anyone looking to buy this, through the coins menu on the app it has a good % off with coins so if you have enough coins you can get it for quite a bit cheaper. I was about to get it for $8.69 CAD and decided to go for the version with the screen for $13.18 CAD. On another note I think this one will do great for quick or remote (no easy access to power) repairs. I already have a KSGER station on my workbench and for remote repair jobs with access to power I have the "PTS100" which is basically a cheaper "clone" of the miniware TS series, but imo it's more ergonomic when using full length T12 tips (same tips used by my station). That one runs on a 65W USB PD adapter. It's in the $30 to $40 range, which is like half of the price of the miniware which got way overpriced when they got popular.

That’s nice! Very useful for testing (questionable) lithium cells.

Thanks!

Thanks for that, I am going to give it another try. I wonder if the DPS-200 is a hint to the future?

These are nice! Mine seems to be stuck in a test loop. Once the power button is pressed it stays on showing a couple screens over and over until the battery dies.

I have seen reviews of the software, however, as I have one of these I would be interested in the software review from yourself. My Win 11 does not seem to work. Thanks Mate

A software review will be appreciated. Thank you.

At 9:52: what big power supply do you used to power up in order to get out the full 30V/ 5A?

Also interested in the PC-Software!

I normally research the bejesus out of things (how i found this video). But I'm hoping I can leverage your knowledge to shortcut that process? I have a full 4 channel pico for car diagnosis. I was looking for a pocket option when out and about. The common one sold to automotive is the Uscope (old dso nano v3). I was hoping for a cheap alternative but there are so many options. What would you suggest for my needs. Mainly 0-5v signals, 0-12v signals, dc amperage signals with frequency abilities. Should i just go the Zeeweii? Or would i get away with the dso152 as my needs are so simple?

The dc jack is (2.5mm x 5mm)? Not (2.5mm x 5.5mm)?

I would guess the metering/measurement setting might be a voltmeter/multimeter type feature.

In case anyone wants to get one of these an d get full power out of it, then 5mm x 2.5mm plug is rarer than hens teeth. However, DigiKey have them (not at Ali-E prices though). The part number is: 1939-1718-ND.

Let's see the PC software!!!

A couple facts for you. #1 FNIRSI has improved the 100W GaN charger late Nov 2024. They told me it is more stable, less likely to burn out when used at high power for a long time. That new charger has yellow on the AC plug side. #2 Although the device can handle higher voltage in it's DC jack, it cannot negotiate 28V with PD3.1 The device has PD3.0 hardware, which can request 20V at max. Perhaps a future version will utilize PD3.1.

The performance is equal to or better than the large bench supplies I have, even more powerful too. I think it would be nicer if it had a physical keypad, though.

Really impressive power supply in small form factor. Glad to have your review. It would be good to figure out how the supply behaves at high output power (>100W) for at least 10min in order to checkout thermal behaviour. Thanks for this review.

Very Nice review, I like this. Fnirsi has been on a roll with these little inexpensive devices. RJ

Transcript Summary: * *0:00** Penlight Meter Backlight Hack Attempt:* Modifying an a3005a penlight meter to always have the backlight on is attempted. * *0:11** Initial Goal:* To enable the backlight permanently, considering the recipient's preference and battery life concerns. * *1:11** Current Draw Measurement:* Turning on the meter draws 1.3mA; enabling the backlight increases it tenfold. * *1:51** Resistance Testing:* A resistance box was used to dim the backlight and reduce current draw, finding a suitable balance at 10k ohms (0.6mA increase). * *3:15** Discovery of Always-On Drawback:* The chosen method would continuously drain the battery, even when the meter is off. * *3:36** Hack Failure:* Due to the circuit design (emitter connected directly to ground), the backlight modification wasn't feasible without constant battery drain. * *4:18** Light Hack:* Modifying 220V lamps to work at 110V * *4:18** Initial Problem:* The creator received 220V lamps instead of the ordered 110V ones. * *4:47** Internal Analysis:* Examined the lamp's circuitry for voltage conversion possibilities. * *5:55** Circuit Board Overview:* The circuit includes a bridge rectifier, linear current sink chips (SM 1082 DS), and LEDs arranged in series-parallel configurations. * *6:21** SM1082DS:* Linear current sink IC's that limit the current to the LED's * *7:08** Modification Strategy:* Cutting traces and using jumper wires to rewire the LEDs in a parallel configuration to reduce the voltage required. * *7:44** Voltage Measurement:* The voltage across each diode series was measured to be around 9.7 volts. * *8:04** Rewiring for 110V:* Cut traces, paralleled LED sections, and removed a current-limiting resistor to reduce the individual LED chip current to 12.5mA. * *8:54** Testing and Success:* After the modification the lamps now draw 50mA and the hack was a success. * *9:11** Grounding:* Successfully grounded the case for safety by bringing the ground to the metal screw. * *9:21** Hack Outcome:* Despite the penlight backlight modification failing, the lamp hack was successful. I used gemini-2.0-flash-exp on rocketrecap dot com to summarize the transcript. However, it required quite a bit of editing including correcting spelling mistakes.

Seems you are putting faith in your digital meter. Keep in mind ensure your digital meter says "true RMS" before you use it as the holy grail.

Re: Which KM601S or HT118E? For tasks which involve; computers, small appliances and electronics and perhaps minor auto applications, which of the two Kaiweets models do you recommend - the KM601S or HT118E? The latter has double the counts but that may not make much differents at the usage noted or does it? What other differences should be considered? Is there another brand at ($50 -$60) that you would recomend instead? Thank-you.

Top!!! Tenho uma carga com 4 mosfet tambem, vou adicionar o pwm e ver como fica. Abraços